Device and method for levitation melting using induction units which are arranged in a tilted manner

Abstract

The invention relates to a levitation melting method and an apparatus for producing casting bodies with tilted induction units. During this method, induction units are employed in which the opposing ferrite poles with the induction coils are not arranged lying in one plane, but tilted at a determined angle to the levitation plane. In this way, an increase in efficiency of the induced magnetic field for melting the batches can be achieved with the induction units. The tilted arrangement increases the portion of the induced magnetic field that effectively contributes to the holding force of the field for levitation of the melt.

Claims

1. A method for producing cast bodies from an electrically conductive material by a levitation melting method, wherein alternating electromagnetic fields levitate a batch, the alternating electromagnetic fields being generated with at least one pair of opposing induction coils with a core of a ferromagnetic material, comprising: introducing a batch of a starting material into a sphere of influence of at least one alternating electromagnetic field so that the batch is kept in a levitating state; melting the batch; positioning a casting mould in a filling area below the levitating batch; casting the entire batch into a casting mould; removing a solidified cast body from the casting mould; wherein the longitudinal axes of the induction coils with their cores are in at least one pair not arranged within a horizontal plane.

2. The method according to claim 1, wherein an angle β between the longitudinal axes of the induction coils with their cores and the horizontal plane in at least one pair is 0°<β≤60°, respectively.

3. The method according to claim 1, wherein an angle β between the longitudinal axes of the induction coils with their cores and the horizontal plane in at least one pair is 10°≤β≤45°, respectively.

4. The method according to claim 1, wherein the induction coils and/or their cores of a ferromagnetic material at least in parts have a frustoconical or conical shape.

5. The method according to claim 1, wherein the induction coils with their cores in each pair are movably arranged relative to each other and move between a melting position with small distance and a casting position with wide distance, the method further comprising: displacing the pairs of induction coils into the melting position with small distance and the casting of the whole batch into the casting mould occurs by moving the induction coils in at least one pair from the melting position with small distance to the casting position with wide distance.

6. The method according to claim 5, wherein during the casting of the batch simultaneously with the movement of the induction coils in the pairs of induction coils from the melting position to the casting position, the current intensity in these induction coils is reduced.

7. The method according to claim 5, wherein the distance of the induction coils in the pairs of induction coil is increased from the melting position to the casting position by 5-100 mm.

8. The method according to claim 5, wherein the distance of the induction coils in the pairs of induction coil is increased from the melting position to the casting position by 10-50 mm.

9. The method according to claim 5, wherein the movement vectors of the induction coils in the pairs of induction coils are not identical to their longitudinal axes.

10. An apparatus for levitation melting an electrically conductive material, comprising: at least one pair of opposing induction coils with a core of a ferromagnetic material for levitating a batch by means of alternating electromagnetic fields, wherein the longitudinal axes of the induction coils with their cores are in at least one pair not arranged within a horizontal plane.

11. The apparatus according to claim 10, wherein the angle β between the longitudinal axes of the induction coils with their cores and the horizontal plane in at least one pair is 0°<β≤60°, respectively.

12. The apparatus according to claim 10, wherein the angle β between the longitudinal axes of the induction coils with their cores and the horizontal plane in at least one pair is 10°≤β≤45°, respectively.

13. The apparatus according to claim 10, wherein the induction coils and/or their cores of a ferromagnetic material at least in parts have a frustoconical or conical shape.

14. The apparatus according to any of claim 10, wherein the induction coils with their cores in each pair are movably arranged relative to each other and move between a melting position with small distance and a casting position with wide distance.

15. The apparatus according to claim 14, wherein the distance of the induction coils in the pairs of induction coils is increased from the melting position to the casting position by 5-100 mm.

16. The apparatus according to claim 14, wherein the distance of the induction coils in the pairs of induction coils is increased from the melting position to the casting position by 10-50 mm.

17. The apparatus according to claim 14, wherein the movement vectors of the induction coils in the pairs of induction coils are not identical to their longitudinal axes.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a lateral cross-sectional view of a casting mould below a melting area with ferromagnetic material, coils and a batch of conductive material.

(2) FIG. 2 is a lateral cross-sectional view of tilted coils.

(3) FIG. 3 is a lateral cross-sectional view of a design variant with frustoconical induction coils and poles.

(4) FIG. 4 is a top view of the coil arrangement of FIG. 3.

(5) FIG. 5 is a lateral perspective view of the coil arrangement of FIG. 3.

DESCRIPTION OF THE FIGURES

(6) The figures show preferred embodiments. They are for illustrative purposes only.

(7) FIG. 1 shows a batch (1) of conductive material which is in the sphere of influence of alternating electromagnetic fields (melting area) generated by the coils (3). Below the batch (1) there is an empty casting mould (2) which is held in the filling area by a holder (5). The casting mould (2) has a funnel-shaped filling section (6). The holder (5) is suitable for lifting the casting mould (2) from a feeding position to a casting position, which is symbolized by the arrow shown. A ferromagnetic material (4) is arranged in the core of the coils (3). The axes of the pair of coils shown dotted in the drawing are tilted downwards to the horizontal plane of levitation, with two opposing coils (3) respectively forming a pair.

(8) FIG. 2 shows a lateral cross-sectional view analogous to FIG. 1 of tilted coils (3) with their cores of ferromagnetic material (4). Here, the horizontal plane is drawn dashed and the angles R are marked, around which the longitudinal axes of the coils (3), depicted in a dotted manner, are tilted out of the horizontal plane.

(9) FIG. 3 shows, in a lateral cross-sectional view, a design variant with frustoconical coils and poles, the latter being depicted in black. The cutting plane runs centrally through the longitudinal axis of a pair of coils. The induction coils (3) and their cores of a ferromagnetic material (4) are frustoconical in shape, respectively, and surrounded by a ferrite ring. In the example shown, the induction coils (3) are designed as hollow-type guides, which additionally offers the option of internal cooling by a cooling fluid. The longitudinal axes of the poles and coils, tilted to the levitation plane, are clearly visible.

(10) FIG. 4 and FIG. 5 show the coil arrangement of FIG. 3 in top and lateral perspective view, respectively. The arrangement consists of two pairs of coils oriented at 90° to each other. The induction coils (3) with their cores of a ferromagnetic material (4) are mounted in a form-fit manner, movably between four ferrite ring segments, so that together an octagonal ferromagnetic element is formed, and they can be moved between a narrowly distanced melting position and a widely distanced casting position. FIGS. 4 and 5 both show the melting position of the coils. In FIG. 5 in particular, the displacement path of the coils between the inside and outside of the ring is clearly visible.

LIST OF REFERENCE NUMERALS

(11) 1 batch 2 casting mould 3 induction coil 4 ferromagnetic material 5 holder 6 filling section